I avoid using more helpers than necessary, so I don't have problems in "normal" modes.
Unless both characters have many moves that spawn permanent (usually killable, but the opponent might let them stay alive) helpers, and the fight was going on for a very long time.
Other than my Seravy character, I don't think something like this would happen in a normal mode on my creations...but on that one...the runes for the spellcasting animation, and the effect/runes that displays his fighting mode are all helpers, plus the bar and card system...up to 10-20 of them even without anything else...plus he has big spells too...and can summon permanent strikers...a lot of them. Not that it matters too much as it's a for fun character anyway, and it really only happens if he fights against himself, and even then it's rare. However you are right in that I could reduce the number of helpers for at least one of those by using more complex code...it just doesn't cause enough problems to make it worth doing, I don't play that character against itself that often...
Simul however is an entirely different matter. 56 helpers/4 players = 14 helpers per player. That can run out easily. And people are actually asking for simul mode of 4vs4 or even more...7 helpers per character if it gets implemented...definitely not enough. I don't play simul, and don't code for it either, as it's the least balanced mode of all of them, but the fact is that it causes problems for that mode much more often.
Then again...having access to more helpers would give us the ability to store more data in variables. If we'd need an array of say 80*60 variables, we could make 80 helpers, and access them as helper(x),var(y)...not that I ever needed one, just saying. Current mugen is too limited to ever need that many variables, but if you could...say read/write data to a file, and code a self-learning AI, that learns from every match, and remembers for the next one, then you'd need it.
So far the most number of variables I needed was about 180, for the 53 card system of the CCS characters.

"deprecated"...it works. Unlike some features that are supposed to work according to the documentation. That's what matters for me. Show me a critical error caused by those helpers and I'll stop using them. At the moment I see that they don't do any more harm than...debug spam._________________Ronin Dream MUGEN Project
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